There's a John Carmack
Q&A on GameSpy.com and a Tim Willits
Q&A on HomeLAN Fed catching up with the id mainstays during QuakeCon.
The Q&A with Willits is an article-format conversation with the id lead
programmer covering various aspects of DOOM 3 development, while also touching
briefly on Quake IV. Quake IV also comes up in the John Carmack Q&A, as id's
lead programmer makes it perfectly clear that their next project will not be
another sequel:

John Carmack:Wolfenstein worked out so
spectacularly well. Inside id there is a group that really, really does not want
to do another sequel. Our next game is not going to be a DOOM, Quake,
or Wolfenstein sequel, it's going to be something new and that is a
foregone conclusion.

We knew that we were going to license that out and let someone do it.

The work that was done with Wolfenstein, in the end it turned out
great, of course, everybody loves it, but it was painful during the development.
At one point we had every programmer at id working, trying to stabilize the code
base to make things okay for shipping.

But still, we looked at that as a success and we are hoping to replicate that
success with Raven doing Quake IV. Raven has always been our lead
engine adopter. It was a foregone conclusion that Raven would get the Doom
engine early, the only question was what they were going to work on.

DOOM is going to be in use for a long time, but just this year, hardware has surpassed a really significant point with the floating point pixel formats and generalized dependent texture reads. These are things that demand that a new engine is written.

The gods command it!

And redoing Quake2 is a good plan. It sounds like GenerationsQ3 done professionally without the foxing They're going to need powerful tools, because even with so much work cut out on development, creating the texturemodels, models and porting the feel is going to be a hell of a lot work.